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41.
Carrie L. Mitchell 《Geoforum》2008,(6):2019-2029
A growing body of literature is concerned with urbanization processes in contemporary Vietnam and how the country’s globalizing cities of Hanoi and Ho Chi Minh City are increasingly becoming spaces of consumption. However, much less is known about how these changing spaces accommodate labour, and in turn support livelihoods. Using published empirical data on Hanoi’s informal waste collectors from 1992 [DiGregorio, M., 1994. Urban Harvest: Recycling as a Peasant Industry in Northern Vietnam. East–West Center, Hawaii, pp. 1–212] and my own data, including a survey of 575 waste collectors and 44 interviews, collected on Hanoi’s informal waste collectors in 2006, I explore the experiences of informal waste collectors (waste pickers and itinerant junk buyers) in Vietnam’s capital city of Hanoi. I argue that Vietnam’s globalizing economy and urban transition have been a catalyst for the growth of the informal waste collector population in Hanoi as well as a partial player in the gendering of this group and the work they undertake. 相似文献
42.
Pollen-inferred vegetation and environmental changes in the central Tibetan Plateau since 8200 yr BP
LingYu Tang CaiMing Shen ChunHai Li JinLan Peng Hui Liu Kam-Biu Liu Carrie Morrill Jonathan T. Overpeck Julia E. Coel Bao Yang 《中国科学D辑(英文版)》2009,52(8):1104-1114
The ecotone between alpine steppe and meadow in the central Tibetan Plateau is sensitive to climate changes. Here we used
the pollen records from three lakes in this region to reconstruct the evolution of local vegetation and climate since 8200
cal. yr BP. The history of temperature and precipitation was reconstructed quantitatively with multi-bioclimatic indexes and
a transfer function from pollen records. Results show that the steppe/meadow dominated during the period of 8200–6500 cal.
yr BP, especially 8200–7200 cal. yr BP, indicating the central Tibetan Plateau was controlled by strong monsoon. The steppe
dominated during the periods of 6000–4900, 4400–3900, and 2800–2400 cal. yr BP. The steppe decreased gradually and the meadow
expanded during the period of 4900–4400 cal. yr BP. Three century-scale drought events occurred during 5800–4900, 4400–3900
and 2800 cal. yr BP, respectively. The first time when the regional climate shifted to the present level was at 6500 cal.
yr BP in the central Plateau. Since 3000 cal. yr BP, the temperature and precipitation have decreased gradually to the present
level. However, the cold climate between 700–300 cal. yr BP likely corresponds to the Little Ice Age.
Supported by Chinese Academy of Sciences 100 Talents Project (Grant No. 29082762), National Natural Science Foundation of
China (Grant Nos. 40671196, 40372085, 49371068, 49871078), and U.S. National Science Foundation (Grant Nos. ATM-9410491, ATM-008194) 相似文献
43.
Samuel E. Tuttle Jennifer M. Jacobs Carrie M. Vuyovich Carrie Olheiser Eunsang Cho 《水文研究》2018,32(6):817-829
In the Northern Great Plains, melting snow is a primary driver of spring flooding, but limited knowledge of the magnitude and spatial distribution of snow water equivalent (SWE) hampers flood forecasting. Passive microwave remote sensing has the potential to enhance operational river flow forecasting but is not routinely incorporated in operational flood forecasting. We compare satellite passive microwave estimates from the Advanced Microwave Scanning Radiometer for the Earth Observing System (AMSR‐E) to the National Oceanic and Atmospheric Administration Office of Water Prediction (OWP) airborne gamma radiation snow survey and U.S. Army Corps of Engineers (USACE) ground snow survey SWE estimates in the Northern Great Plains from 2002 to 2011. AMSR‐E SWE estimates compare favourably with USACE SWE measurements in the low relief, low vegetation study area (mean difference = ?3.8 mm, root mean squared difference [RMSD] = 34.7 mm), but less so with OWP airborne gamma SWE estimates (mean difference = ?9.5 mm, RMSD = 42.7 mm). An error simulation suggests that up to half of the error in the former comparison is potentially due to subpixel scale SWE variability, limiting the maximum achievable RMSD between ground and satellite SWE to approximately 26–33 mm in the Northern Great Plains. The OWP gamma versus AMSR‐E SWE comparison yields larger error than the point‐scale USACE versus AMSR‐E comparison, despite a larger measurement footprint (5–7 km2 vs. a few square centimetres, respectively), suggesting that there are unshared errors between the USACE and OWP gamma SWE data. 相似文献
44.
Amy J. Wagner Carrie Morrill Bette L. Otto-Bliesner Nan Rosenbloom Kelsey R. Watkins 《Climate Dynamics》2013,41(11-12):2855-2873
Previous model experiments of the 8.2 ka event forced by the drainage of Lake Agassiz often do not produce climate anomalies as long as those inferred from proxies. In addition to the Agassiz forcing, there is new evidence for significant amounts of freshwater entering the ocean at 8.2 ka from the disintegration of the Laurentide ice sheet (LIS). We use the Community Climate System Model version 3 (CCSM3) to test the contribution of this additional meltwater flux. Similar to previous model experiments, we find that the estimated freshwater forcing from Lake Agassiz is capable of sustaining ocean and climate anomalies for only two to three decades, much shorter than the event duration of ~150 years in proxies. Using new estimates of the LIS freshwater flux (~0.13 Sv for 100 years) from the collapse of the Hudson Bay ice dome in addition to the Agassiz drainage, the CCSM3 generates climate anomalies with a magnitude and duration that match within error those from proxies. This result is insensitive to the duration of freshwater release, a major uncertainty, if the total volume remains the same. An analysis of the modeled North Atlantic freshwater budget indicates that the Agassiz drainage is rapidly transported out of the North Atlantic while the LIS contribution generates longer-lasting freshwater anomalies that are also subject to recirculation by the subtropical gyre back into the North Atlantic. Thus, the meltwater flux originating from the LIS appears to be more important than the Agassiz drainage in generating 8.2 ka climate anomalies and is one way to reconcile some model-data discrepancies. 相似文献
45.
Organic farmers are a prime clientele for climate services by virtue of their social profile and vulnerability of produce to climate extremes. The study draws on an online survey and in-depth interviews with organic farmers in Georgia (United States). It shows that organic farmers access and act on climate information in ways that reflect their emphasis on diversified and flexible systems. They favor a pluralistic knowledge base that integrates scientific expertise with place-based experience and intuitive understandings. Their management style combines information at multiple temporal scales and draws on a range of technical and social resources. Translating climate forecasts into usable science for organic farming requires attention to the identities, commitments, and relationships that define the organic farming community. 相似文献
46.
Water, sponge and coral samples were collected from stations impacted by a variety of pollution sources and screened for human enteric viruses as conservative markers for human sewage. While human enteroviruses and adenoviruses were not detected, noroviruses (NoV; human genogroups I and II) were detected in 31% of samples (especially in sponge tissue). Stations near inlets were the only ones to show multiple sample types positive for NoV. Fecal indicator bacteria and enteric viruses were further evaluated at multiple inlet stations on an outgoing tide. Greatest indicator concentrations and highest prevalence of viruses were found at the mouth of the inlet and offshore in the inlet plume. Results suggest that inlets moving large volumes of water into the coastal zone with tides may be an important source of fecal contaminants. Efforts to reduce run-off or unintended release of water into the Intracoastal Waterway may lower contaminants entering sensitive coastal areas. 相似文献
47.
Ecosystem-based management (EBM), despite the best efforts of managers, researchers, and policy makers, often falls short of its intended purpose resulting in inadequate protection of resources. Coastal habitats are particularly vulnerable to poor management due to high use and potential for user conflict. EBM can be improved when it is informed by ecological science and considers the socio-economic needs of the community. Communication between scientists and stakeholders can help to prevent adverse outcomes while enhancing protection and sustainability of the coastal environment. In the research presented here, a framework is used to guide and enhance communication between scientists and stakeholders for sustainable management of resources and equity of all users. The outcome of this applied framework is a long-term plan to guide the management of an oyster aquaculture industry using carrying capacity as an estimate for the basis of management decisions. Central to the framework is the Working Group on Aquaculture Regulations (WGAR), which represents a diverse group of stakeholders. The WGAR worked closely with ecological modelers over a two-year period using mass-balance modeling to calculate ecological carrying capacity for oyster aquaculture in two ecosystems: Narragansett Bay and a set of highly flushed temperate lagoons in Rhode Island, USA. Collaboration between scientists and the WGAR greatly improved the models and stakeholder understanding of the science and acceptance of the results. Aquaculture is increasing in coastal regions world-wide and this framework should be easily transferable to other areas suffering from similar user conflict issues. 相似文献
48.
Climate Dynamics - The East Asian winter monsoon (EAWM) exhibits significant variability on intraseasonal, interannual, and interdecadal time scales and the variability can be extended to Holocene... 相似文献
49.
Analysis of tidal marsh vegetation patterns in two Georgia estuaries using aerial photography and GIS 总被引：1，自引：0，他引：1
Aerial photographs and GIS analysis were used to map the distribution of tidal marsh vegetation along the salinity gradients
of the estuaries of the Altamaha and Satilla Rivers in coastal Georgia. Vegetation maps were constructed from 1993 U.S. Geological
Survey Digital Orthophoto Quarter Quads, 1∶77,000-scale color infrared photographs taken in 1974 and 1∶24,000-scale black
and white photographs taken in 1953, Changes between years were identified using a GIS overlay analysis. Four vegetation classifications
were identified and groundtruthed with field surveys: salt marsh (areas containing primarilySpartina alterniflora), brackish marsh (Spartina cynosuroides andS. alterniflora), Juncus (Juncus roemerianus), and fresh marsh (Zizania aquatica, Zizaniopsis miliacae, and others). There was no evidence for an upstream shift in marsh vegetation along the longitudinal axis of either estuary
over the time frame of this analysis, which implies there has not been a long-term increase in salinity. Although the inland
extent of each marsh zone was further upstream in the Satilla than the Altamaha, they corresponded to similar average high
tide salinities in each estuary: areas classified as salt marsh occurred from the mouth up to where average high tide salinity
in the water was approximately 15 psu;Juncus ranged from 21 to 1 psu; brackish marsh ranged from 15 to 1 psu; and fresh marsh was upstream of 1 psu. Approximately 63%
of the 6,786 ha of tidal marsh vegetation mapped in the Altamaha and 75% of the 10,220 ha mapped in the Satilla remained the
same in all 3 yr.Juncus was the dominant classification in the intermediate regions of both estuaries, and shifts between areas classified asJuncus and either brackish or salt marsh constituted the primary vegetation change between 1953 and 1993 (87% of the changes observed
in the Altamaha and 95% of those in the Satilla). This analysis suggests that the broad distribution of tidal marsh vegetation
along these two estuaries is driven by salinity, but that at the local scale these are dynamic systems with a larger number
of factors affecting the frequently changing borders of vegetation patches. 相似文献
50.
Researchers have been analyzing the costs of carbon sequestration for approximately twelve years. The purpose of this paper is to critically review the carbon sequestration cost studies of the past dozen years that have evaluated the cost-effectiveness of the forestry option. Several conclusions emerge. While carbon sequestration cost studies all contain essentially the same components they are not comparable on their face due to the inconsistent use of terms, geographic scope, assumptions, program definitions, and methods. For example, there are at least three distinct definitions for a `ton of carbon' that in turn lead to significantly different meanings for the metric `dollars per ton of carbon'. This difference in carbon accounting further complicates comparison of studies. After adjusting for the variation among the studies, it appears that carbon sequestration may play a substantial role in a global greenhouse gas emissions abatement program. In the cost range of 10 to 150 dollars per ton of carbon it may be possible to sequester 250 to 500 million tons per year in the United States, and globally upwards of 2,000 million tons per year, for several decades. However, there are two unresolved issues that may seriously affect the contribution of carbon sequestration to a greenhouse gas mitigation program, and they will likely have counteracting effects. First, the secondary benefits of agricultural land conversion to forests may be as great as the costs. If that is the case, then the unit costs essentially disappear, making carbon sequestration a no-regrets strategy. In the other direction, if leakage is a serious issue at both the national and international levels, as suggested by some studies, then it may occur that governments will expend billions of dollars in subsidies or other forms of incentives, with little or no net gain in carbon, forests or secondary benefits. Preliminary results suggest that market interactions in carbon sequestration program analyses require considerably more attention. This is especially true for interactions between the forest and agricultural land markets and between the wood product sink and the timber markets. 相似文献